This invention was made in the course of research sponsored by the National Institutes of Health. The U.S. Government may have certain rights in this invention.
Cardiovascular disease is the leading cause of mortality in the western world (Ross, R. Nature 362, 801-809 (1993); Landau et al. N. Engl. J. Med. 330, 981-993 (1994)) In the United States and other industrialized countries ischemic heart disease, resulting in angina pectoris, myocardial infarction (MI), and sudden death, prevails as the principal cause of death and comprises at least 80% of all deaths from heart disease (Braunwald, E. In Heart disease: a textbook of cardiovascular medicine. Saunders W. B. Ed., (1996)) The vast majority of cases of ischemic heart disease are a consequence of atherosclerosis of the coronary arteries (Ross, R Nature 362, 801-809 (1993)). The treatment of occlusive coronary artery disease (CAD) involves three approaches, used individually or in combination: 1) coronary artery by-pass grafting (CABG); 2) percutaneous transluminal coronary angioplasty (PTCA), with or without stent application; and/or 3) medical management. While PTCA is less invasive and more cost effective than CABG, it bears some limitations. One disadvantage of PTCA is that restenosis of the artery occurs in as many as 30 to 50% of cases within 3 to 6 months of the procedure (Landau et al. N. Engl. J. Med. 330,981-993 (1994); Braunwald, E. In Heart disease: a textbook of cardiovascular medicine. Saunders W. B. Ed., (1996); Serruys et al. Circulation. 77,361-71 (1988); Holmes et al. Am. J. Cardiol. 53, 77C-81C (1984); Guiteras et al. Am. J. Cardiol. 60, 50B-55B (1987)) . A variation of this technique is stent application in the dilated artery segment. Following promising preliminary reports, further investigation demonstrated that in the long-term the percentage of restenosis following stent-PTCA is similar to that of PTCA alone. In fact, in-stent restenosis is a frequent complication of stent-PTCA (Belli, G., Ellis, S. G., Topol, E. J. Stenting for ischemic heart disease. In xe2x80x9cprogress in cardiovascular diseasesxe2x80x9d W. B. Sunders Ed. pp 159-182 (1997)). No effective treatment for hindering restenosis is currently available. It is well documented that chronic or acute injury (such as from PTCA) to the arterial wall induces the expression of a variety of growth factors and inflammatory cytokines that stimulate smooth muscle cell (SMC) proliferation and migration from the media into the intirna resulting in neointima formation and eventual restenosis (Clowes et al. Lab. Invest. 49, 208-215 (1983)). Inhibition of neointima formation should greatly improve the effectiveness of PTCA in the long term management of CAD. Numerous growth factors induce SMC proliferation through a variety of signal transduction pathways in vitro and in vivo (Libby et al. Circulation 86 (Suppl III) 47-52 (1992)). Accordingly, several regulatory proteins of the cell cycle machinery, instead of the upstream signal transduction molecules, have been suggested as targets for effective cytostatic therapy of vascular proliferative disorders. For example, Morishita et al. disclose studies wherein single intraluminal delivery of antisense cdc2 kinase and proliferating-cell nuclear antigen oligonucleotides resulted in chronic inhibition of neointimal hyperplasia. Proc. Acad. Natl. Sci. 90, 8474-8478 (1993). Chang et al. disclose results from studies suggested to demonstrate the role of (retinoblastoma) Rb in regulating vascular smooth muscle cell proliferation and to suggest a gene therapy approach for vascular proliferation disorders associated with arterial injury. Science. 267, 518-522 (1995). Smith et al. also analyzed the effects of full-length phosphorylation competent and mutant truncated forms of human Rb for their effects on vascular smooth muscle proliferation and neointima formation. Circulation 1997 96(6) 1717-9. These analyses are taught to reveal that the maintenance of high levels of phosphorylation competent human Rb either full-length or truncated forms in vascular smooth muscle cells is an effective method of modulating the extent of intimal hyperplasia that occurs after balloon induced vascular injury. Smith et al. Circulation. 96, 1899-1905 (1997)).
Another member of the retinoblastoma family, RB2/p130, has also been shown to have a regulatory role in cell cycle function. Baldi et al. have shown that phosphorylation of the RB2/pl30 gene product is regulated in a cell cycle dependent manner (Baldi et al. J. Cell. Biochem. 59:402-408 (1995)), in the same way that the phosphorylation of Rb is cell cycle dependent (DeCaprio et al. Cell 58:1085-1095 (1989)). Further, the growth suppressive properties of the gene product of RB2/pl30 have been shown to be specific for the G1 phase in similar fashion to pRb and pl07 (Claudio et al. Cancer Res. 56:2003-2008 (1996)). The gene product of RB2/pl30 has also been shown to arrest growth in human tumor cell lines in a manner similar to the other members of the Rb family (i.e., pRb and pl07). However, this protein also inhibits proliferation in a glioblastoma cell line that is resistant to the growth suppressive effects of both pRb and pl07 (Claudio et al. Cancer Res. 54:5556-5560 (1994)). Accordingly, RB2/pl30 has similar yet distinctive growth suppressive properties from pRb and pl07 (Claudio et al., Cancer Res. 54:5556-5560 (1994)).
It has now been found that localized arterial transduction of RB2/pl30 via a viral vector at the time of angioplasty drastically reduces neointimal hyperplasia and prevents restenosis. Furthermore, the ability of RB2/pl30 to block proliferation correlates with its ability to bind and sequester the E2F family of transcription factors, which are important mediators of cell cycle progression. Accordingly, RB2/pl30 is believed to be an important target for vascular gene therapy.
An object of the present invention is to provide a method of inhibiting vascular smooth muscle cell proliferation which comprises transducing vascular smooth muscle cells with a viral vector expressing RB2/pl30.
Another object of the present invention is to provide a method of preventing restenosis in a patient which comprises administering to a patient a viral vector expressing RB2/pl30.